Waning antibody levels after vaccination with mRNA BNT162b2 and inactivated CoronaVac COVID-19 vaccines in Hong Kong blood donors

Both inactivated vaccine (CoronaVac; Sinovac) and mRNA vaccine (Comirnaty/BNT162b2; Fosun-Pharma/BioNTech) are available in Hong Kong’s COVID-19 Vaccination Programme. We reported waning antibody levels by enzyme-linked immunosorbent assays (ELISA) and surrogate virus neutralization test (sVNT) among 850 fully vaccinated blood donors (i.e., received two doses). The BNT162b2 group’s antibody levels remain over the 50% protection threshold within six months, and the CoronaVac’s group’s median antibody levels begin to fall below the 50% protection threshold two months after vaccination.

Plasma Proteome Changes Linked to Late Phase Response After Inhaled Allergen Challenge in Asthmatics

BackgroundA subset of individuals with allergic asthma develops a late phase response (LPR) to inhaled allergens, which is characterized by a prolonged airway obstruction, airway inflammation and airway hyperresponsiveness. The aim of this study was to identify changes in the plasma proteome and circulating hematopoietic progenitor cells associated with the LPR following an inhaled allergen challenge. MethodsSerial plasma samples from asthmatics undergoing inhaled allergen challenge were analyzed by mass spectrometry and immunosorbent assays. Peripheral blood mononuclear cells were analyzed by flow cytometry. Mass spectrometry data was analyzed using a linear regression to model the relationship between airway obstruction during the LPR and plasma proteome changes. Data from immunosorbent assays was analyzed using linear mixed models.ResultsOut of 396 proteins quantified in plasma, 150 showed a statistically significant change 23 h post allergen challenge. Among the most upregulated were three protease inhibitors: alpha-1-antitrypsin, alpha-1-antichymotrypsin and plasma serine protease inhibitor. Altered levels of 13 proteins were associated with the LPR, including increased factor XIII A and a decreased von Willebrand factor. No relationship was found between the LPR and changes in the proportions of classical, intermediate, and non-classical monocytes.ConclusionsAllergic reactions to inhaled allergens in asthmatic subjects was associated with changes in a large proportion of the measured plasma proteome, whereof protease inhibitors showed the largest changes, likely to influence the inflammatory response. Many of the proteins altered in relation to the LPR are associated with coagulation, highlighting potential mechanistic targets for future treatments of type-2 asthma.

Saliva-Based ELISAs for Effective SARS-CoV-2 Antibody Monitoring in Vaccinated Individuals

In March 2020, the World Health Organization (WHO) declared a global health emergency—the coronavirus disease 2019 (COVID-19) pandemic. Since then, the development and implementation of vaccines against the virus amidst emerging cases of re-infection has prompted researchers to work towards understanding how immunity develops and is sustained. Serological testing has been instrumental in monitoring the development and persistence of antibodies against SARS-CoV-2 infection, however inconsistencies in detection have been reported by different methods. As serological testing becomes more commonplace, it is important to establish widespread and repeatable processes for monitoring vaccine efficacy. Therefore, we present enzyme linked immunosorbent assays (ELISAs) compatible for antibody detection in saliva as highly accurate, efficacious, and scalable tools for studying the immune response in individuals vaccinated against SARS-CoV-2.

Sero-surveillance for SARS-CoV-2 infection among healthcare providers in four hospitals in Thailand one year after the first community outbreak

Background Thailand was the first country outside China to report SARS-CoV-2 infected cases. Since the detection of the first imported case on January 12th, 2020 to the time this report was written, Thailand experienced two waves of community outbreaks (March-April 2020 and December 2020-March 2021). We examined prevalence of SARS-CoV-2 seropositivity among healthcare providers (HCPs) in four hospitals approximately one year after SARS-CoV-2 first detected in Thailand. By March 2021, these hospitals have treated a total of 709 coronavirus disease 2019 (COVID-19) patients. Methods Blood specimens, collected from COVID-19 unvaccinated HCPs during January-March 2021, were tested for the presence of SARS-CoV-2 immunoglobulin G (IgG) antibodies to nucleocapsid (IgG-nucleocapsid) and spike (IgG-spike) proteins using Euroimmune® enzyme-linked immunosorbent assays. Results Of 600 HCPs enrolled, 1 (0.2%) tested positive for the SARS-CoV-2 IgG-spike antibodies, but not the IgG-nucleocapsid. Conclusion The presence of SARS-CoV-2 IgG antibodies was rare in this sample of HCPs, suggesting that this population remains susceptible to SARS-CoV-2 infection.

Toxoplasma gondii Infection and Suicidal Behavior in People with Alcohol Consumption

We determined the association between T. gondii infection and suicidal behavior in people with alcohol consumption. One-thousand four-hundred and twenty-three people with alcohol consumption were screened for suicidal behavior and tested for anti-T. gondii IgG and IgM antibodies using commercially available enzyme-linked immunosorbent assays. Anti-T. gondii IgG antibodies were found in 34 of 224 (15.2%) individuals with suicidal ideation and in 118 (9.8%) of 1199 individuals without suicidal ideation (OR: 1.63; 95% CI: 1.08–2.47; p = 0.01). Seropositivity to T. gondii was associated with suicidal ideation in women (OR: 2.24; 95% CI: 1.33–3.78; p = 0.001) and in individuals aged ≤30 years (OR: 2.68; 95% CI: 1.22–5.87; p = 0.01) and >50 years (OR: 2.85; 95% CI: 1.19–6.77; p = 0.01). Anti-T. gondii IgG antibodies were found in 17 of 136 (12.5%) individuals with suicide attempts and in 135 (10.5%) of 1287 individuals without suicide attempts (OR: 1.21; 95% CI: 0.71–2.08; p = 0.47). Seroprevalence of T. gondii infection was associated with suicide attempts in women (OR: 1.88; 95% CI: 0.99–3.55; p = 0.04). No association between anti-T. gondii IgM and suicidal ideation or suicide attempts was found. Results suggest that T. gondii infection is associated with suicidal behavior in people with alcohol consumption.